Maternal age is associated with embryo splitting after single embryo transfer: a retrospective cohort study
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ASSISTED REPRODUCTION TECHNOLOGIES
Maternal age is associated with embryo splitting after single embryo transfer: a retrospective cohort study Xitong Liu 1 & Juanzi Shi 1 Received: 24 August 2020 / Accepted: 19 October 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Purpose To determine whether maternal age has an impact on monozygotic twinning (MZT) rates in women undergoing single embryo transfer (SET). Methods This is a retrospective cohort study analyzed for the incidence of MZT of all clinical pregnancies after a single embryo transfer was carried out between 2014 and 2018. The effect of different assisted reproductive technology (ART) parameters on the incidence of MZT was evaluated. Results There were a total of 8459 cycles resulting in pregnancy during the study period. Of these pregnancies, 8236 were singletons and 223 were MZT. The preterm birth rate, miscarriage rate, and cesarean section rate were higher in MZT. Birth weight and gestational age at delivery were lower and smaller. In the univariate analysis, the risk of MZT was decreased with frozen embryo transfer (ET). A nonlinear relationship was observed between maternal age and MZT. A negative relationship between maternal age and MZT was observed in the patients’ age ≥ 36 years. Conclusion Advanced maternal age was associated with a lower rate of MZT. A threshold female age of 36 years existed for lower MZT. Keywords IVF . Monozygotic twins . Maternal age
Introduction In vitro fertilization (IVF) treatment is complicated by a high rate of multiple-gestation pregnancies [1]. Elective single embryo transfer (eSET) has been proposed as a way of obtaining singleton pregnancies, which has been advocated in many IVF centers worldwide. Although eSET is capable of reducing multiple pregnancy rates, it can still arise due to the early splitting of the embryo resulting in two identical twins [2]. Monozygotic twinning (MZT) is known to carry a significantly higher risk of perinatal morbidity and mortality than singleton and dizygotic twins [3], such as twin-to-twin transfusion syndrome, which occurs in 10–20% of MZT [4]. The occurrence of monozygotic twinning in spontaneous conceptions is estimated to be approximately 0.4–0.45%. In contrast, the incidence of MZT after ART is higher (2–12-fold) [5–8]. MZT could have a significant
effect on clinical outcomes and needs particular attention. Although the risk factors and mechanisms responsible for embryo splitting are still under discussion, it has been argued that IVF procedure and patient characteristics may play an important role in the development of MZT. Previous studies have pointed out that blastocyst transfer [9], assisted hatching (AH) [10], and oocyte age [11] may affect the risk of MZT pregnancies, while other studies contradict these findings. Therefore, our aim was to determine whether maternal age has an impact on MZT rates in women undergoing single embryo transfer.
Materials and methods Ethical approval
* Juanzi Shi [email protected] 1
The Assisted Repr
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